<template>
  <div>
    <h2>当前求和为：{{sum}}</h2>
    <div>
      <select v-model="n">
        <option :value="1">1</option>
        <option :value="2">2</option>
        <option :value="3">3</option>
      </select>
      <button @click="increment">+</button>
      <button @click="decrement">-</button>
      <button @click="incrementOdd">当前求和为奇数再加</button>
      <button @click="incrementWait">等一等再加</button>
    </div>
  </div>
</template>

<script>
  export default {
    name:'Count',
    data() {
      return {
        sum: 0,
        n: 1// 用户当前选择的值
      }
    },
    methods:{
      increment(){
        this.sum += this.n
      },
      decrement(){
        this.sum -= this.n
      },
      incrementOdd(){
        if(this.sum % 2){
          this.sum += this.n
        }
      },
      incrementWait(){
        setTimeout(()=>{
          this.sum += this.n
        },1000)
      }
    }
  }
</script>

<style>
  button {
    margin-left: 10px;
  }
</style>